[Shared decision-making and communication theory: grounding the tango].

Shared decision-making (SDM) has the potential to overcome outdated social role models in the health care system. The concept, however, adheres to archaic epistemological assumptions as can be inferred from the rudimentary stage of the measurement methods used and from the information monopoly that the physician still holds in this concept. Advantages of an up-to-date model of knowledge for understanding and operationalising SDM are outlined. To this purpose, essential definitions of the concept are reflected in terms of epistemology. Accordingly, information emerges through a process of social construction. Likewise, interpersonal relations do not represent a static condition; rather, they develop anew with each interaction. Therefore, constructs suitable to focus on dyadic interaction processes can be used as indicators of sharing in SDM. Theories and methods of the interpersonal paradigm are advocated.